Some of 2025's leaders have returned to the list. Others have not, reflecting changes to the economy and the market's mood.What a year for the stock market! Not a bad one -- as of the latest look, the S&P 500 is actually on track to log a 2025 gain of nearly 20%.It's just been a wild (and sometimes confusing) year, led by artificial intelligence (AI) powerhouses like Nvidia, while stalwarts like Apple (AAPL 0.49%) and Amazon have lagged. International trade tensions and lingering inflation have made things ...